What does my body do with the water I drink?January 24, 2014 10:49 PMSubscribe

What happens to the drinking water I swallow? All I know is that it goes down my throat to my stomach, and then my body does its thing. Can you go into greater detail for me? For example: What positive effects does the water I drink have on my mouth, my throat, my stomach and other parts of my body? How does the stomach process the water? Where does the water go after my stomach? How does what's in the water get from my stomach to the necessary parts of my body? What's in water that my body needs? What parts of my body benefit the most from the water I drink? Feel free to answer other relevant questions that I've overlooked.posted by paleyellowwithorange to Health & Fitness (9 answers total) 19 users marked this as a favorite

Your kidneys maintain homeostasis. If you drink extra water, you'll just piss it out.posted by mr_roboto at 11:26 PM on January 24, 2014

This paper covers some of the key areas of what your body does with water, how it is lost, etc.posted by biffa at 1:14 AM on January 25, 2014 [2 favorites]

To answer part of your question, water goes from the stomach to the small intestine, which absorbs most of it and passes it into the bloodstream.posted by Specklet at 4:25 AM on January 25, 2014

Water is needed by each of your cells. Water in the bloodstream keeps the heart and kidneys working. Water in the bloodstream is needed to carry blood cells, oxygen, and nutrients to the cells and to carry waste products from the cells and to the kidneys. The kidneys filter out from the blood the waste products that must be excreted. The water from the kidneys carries those products to the bladder and from there to the outside world.

What positive effects does the water I drink have on my mouth, my throat, my stomach and other parts of my body?

Water is pretty much the substrate on which your entire body is built. Everything in your body with the possible exception of your bones is either dissolved in, suspended in, or surrounds a tiny drop of water.

How does the stomach process the water?

It basically doesn't. Water is already in an appropriate form to be absorbed, so all the stomach does is hang onto it for a while if it's busy digesting other things.

How does what's in the water get from my stomach to the necessary parts of my body?

The wall of your small intestine basically works like terry towelling; it's covered in tiny fingers that filter the liquid part of whatever's on the way through and transfer it to capillaries in the intestinal wall. That adds it to your blood, which goes pretty much everywhere in your body.

Every single cell in your body has a "smart" wall that will accept water from or reject water into the bloodstream as necessary to maintain its internal operations.

By the time it's been mixed with everything else travelling through your stomach and gut, it will have assorted other nutrients dissolved in it and these also migrate with it through the gut wall into the bloodstream. So, pretty much everything you eat.

What parts of my body benefit the most from the water I drink?

All of it, especially your muscles.

Your body maintains the concentrations of stuff dissolved in its water very carefully, and excess water gets rejected via your kidneys along with other stuff that your blood contains more of than it needs to, and dumped into your bladder as urine.

If your urine looks very dark, that's an indication that your kidneys have a less than optimal amount of water to flush everything else through with and will be operating at somewhat reduced efficiency as a result. Other indications that you're running short on water are a dry mouth, a feeling of thirst, being easily fatigued and so on.

By the way, your body also produces a certain amount of water as a byproduct of metabolizing food: food metabolism is essentially a complicated and circuitous form of combustion, and the hydrogen from the fats, carbohydrates and some of the protein you burn gets combined with the oxygen you breathe to form water that ends up in your cells, which will dump some of it into your bloodstream.

Once that's happened, it's chemically and therefore functionally identical to water you've ingested in liquid form.posted by flabdablet at 7:09 AM on January 25, 2014 [1 favorite]

Basically all of the water you drink gets absorbed by the small intestine and it adds to your blood volume. Blood, roughly speaking, consists of a liquid part and a cell and cell material part (red/white cells, platlets, antibodies...etc). All that water you drank goes into liquid portion of the blood and therefore decreases the concentration of the blood. This isn't necessarily a bad thing. You can be dehydrated and by drinking water, you increase your blood volume to the normal levels. Some of the water (typically called free water) in your blood eventually gets redistributed into the tissues in your body. How this happens depends on osmosis and is affected by the concentration of sodium in your blood.

Your body depends on your blood having the right concentration of electrolytes. The amount of water you drink has an effect on this concentration, but this concentration crucially depends on your kidney function as well as your endocrine system to keep the electrolyte levels in the right range. I won't go into great detail here, but bad things can happen if any of the electrolytes are out of whack. As I mentioned, sodium levels in your blood primarily affect how much of the water is distributed in the tissues compared to the blood. Potassium is a crucial electrolyte for cellular function, and has a key role in allowing your muscles to contract and nerves to send action potentials. High or low levels of potassium can cause your heart, one of the most important muscles in your body, to malfunction.

So, while water is necessary for survival, I would be hard pressed to identify a specific effect on an organ that can be attributed to drinking more water.posted by scalespace at 7:10 AM on January 25, 2014 [3 favorites]

So, while water is necessary for survival, I would be hard pressed to identify a specific effect on an organ that can be attributed to drinking more water.

This was an excellent answer from scalespace. To add to it, in a normal healthy person, water goes in, the body adjusts based on its relative need for circulating blood volume and electrolyte balance, and excess water is removed in the form of urine. Consequently to a point, the primary effect of drinking more water is your kidneys making more urine. A more proximate effect of water intake is also that though the gut absorbs the vast majority of water that passes through it, how much you drink may effect your stool water content. As a result, inadequate water intake may cause overly hard stool and constipation. On a side note, what you drink accounts for a minority of water the gut absorbs since on a daily basis you produce and re-absorb over 6 liters of your own saliva and secretions along with most of what you drink. You are also constantly losing water in the form of things like sweat and breathing.

There are a variety of illnesses (most notably heart failure, kidney failure, and liver failure) where the complex mechanisms that maintain tight control over your body fluid and electrolyte balance get out of whack. In people with these conditions, inappropriate fluid retention is a common complication, leading to swelling, trouble breathing due to accumulation of water in the lungs (pulmonary edema), as well as water accumulation in other places it doesn't belong.posted by drpynchon at 6:29 PM on January 25, 2014 [1 favorite]

Consequently to a point, the primary effect of drinking more water is your kidneys making more urine.

And that urine will be more dilute, and therefore lighter in colour.

If your urine appears essentially colourless, and you have no trouble crapping, you could probably afford to back off a little on how much water you're drinking.posted by flabdablet at 6:33 PM on January 25, 2014

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